New subsidence guidelines from the Department of Water Resources are expected to drop on San Joaquin Valley water managers any day, a prospect that has them both hopeful and worried.

The intent of the guidelines is to provide clarity within the Sustainable Groundwater Management Act,  which requires over-drafted regions to enact plans to bring aquifers into balance by 2040.

One of SGMA’s primary goals is to halt subsidence, land sinking.

Understanding Subsidence and Its Impacts

Excessive groundwater pumping has caused huge swaths of the San Joaquin Valley to sink, damaging canals, roads and increasing flood risks. Some areas have collapsed on such a large scale, the phenomenon can be seen from space, earning the nickname  “the Corcoran bowl.”

Subsidence, though, has been a tricky devil to manage.

Not all subsidence is the same. Some is reversible with substrata and aquifers that act like sponges, contracting in drought, refilling in wet years. In other areas, sinking is irreversible, particularly when pumping occurs deep below what’s known as the Corcoran clay layer that lies beneath the valley’s surface in intermittent patches.

The only sure way to stop subsidence is to stop pumping.

But that means a drastic reduction in farming. Current estimates already show 600,000 acres will have to come out of production in Tulare, Kings and Kern counties alone.

All of which means, water managers, farmers and others are nervously awaiting DWR’s new subsidence guidelines.

Anticipation and Uncertainty Among Water Managers

So far, all that’s known is from a few mentions of the new guidelines by DWR Director Paul Gosselin at two state Water Resources Control Board meetings.

At a meeting in April, Gosselin said of the pending guidelines: “…this is going to be a significant action for (Groundwater Sustainability Agencies.)”

That immediately caught the attention of local water managers.

As did Gosselin’s statement that stopping subsidence will “cause a significant ask on land transition, so there will have to be a considerable state effort in these areas because you are dealing with a lot of ag transition, jobs and community impacts.”

At a June 3 Water Board meeting, he added that the new guidelines will employ “a much more interactive process” with GSAs.

Details, however, are still under wraps.

SJV Water asked DWR for more information and was told only that the agency would release a draft of the guidelines, conduct outreach, answer questions, take feedback, etc.

No date was given for that release.

In the meantime, water managers are left to speculate as to what the guidelines could mean locally.

Local Perspectives on the Coming Guidelines

For some, increased focus on subsidence is welcome, said Eric R. Quinley, manager of Delano-Earlimart Irrigation District and GSA in the Tule subbasin in southern Tulare County.

He said new guidelines are “necessary and urgent,” adding that the existing SGMA framework has continued to allow, even encourage, excessive pumping.

Delano-Earlimart has made groundwater recharge a priority for years and was singled out by the Water Board as “sustainable” when the Tule subbasin was put on probation in 2024. Consequently, its farmers aren’t required to report extractions and pay fees as are farmers in neighboring GSAs.

Quinley said it’s critical that new guidelines address how subsidence from those neighboring GSAs impacts other areas.

“Our pipeline distribution system was not designed to withstand the levels of unsustainable overdraft that are taking place in the Tule subbasin,” he said.

Other water managers have greater trepidation about the coming guidelines.

“It will be… troublesome if they suggest too aggressive of a level of effort,” said Mark Larsen, general manager of Greater Kaweah GSA, whose boundaries stretch across Tulare County’s northern flatlands and a portion of Kings County.

He said his GSA is considering the impacts of limiting pumping from deeper wells, which has a potential to depressurize confined aquifers and induce subsidence.

“That will be a hardship for a lot of western farming operations who have tapped wells deeper and deeper in response to well failures in drought years,” Larsen said. “This will add another restriction that will significantly reduce their options and challenge their ability to adjust to farming with less.”

Smart Approaches to Land Retirement

Deanna Jackson is manager at Tri-Counties Water Authority, which straddles the Tule and Tulare Lake subbasins in southern Tulare and Kings counties.

Like the Tule subbasin, the Tulare Lake subbasin was placed on probation last year for lacking an adequate groundwater management plan.

Runaway subsidence in both subbasins was a major factor.

Excessive pumping caused land to sink beneath a 33-mile section of the Friant-Kern Canal in the Tule subbasin, crimping its carrying capacity by 60%. Subsidence in southern Kings County altered flood plains and caused the levee protecting Corcoran to sink, requiring it to be raised twice since 2016.

Jackson said while groundwater levels have begun to stabilize and sustainability is in reach by 2040, the state must deliver funding for land retirement programs in the most critical areas to systematically retire certain lands.

“Driving farms and dairies out of business through financial devastation should not be the only choice,” she said. “Unorganized land retirement brings grave consequences: job loss, county tax revenue loss, and environmental hazards, to name a few.”

About the Author

Lisa grew up in Tulare County. She has reported on agriculture and other issues for a wide variety of publications, including, Ag Alert, Visalia Times-Delta, the Fresno Bee and the Tulare and Kings counties farm bureau publications. She is a graduate of Cal Poly, San Luis Obispo’s journalism program and has earned a certificate in Technical Communication from Arizona State University.

About SJV Water

SJV Water is an independent, nonprofit news site covering water in the San Joaquin Valley, www.sjvwater.org. Email us at sjvwater@sjvwater.org.